ABSTRACT
All sensory information from multimodal and association neocortical areas converges on hippocampus and amygdala, which are in located the ventromedial portion of the temporal lobe. The hippocampus can be divided into two subregions: the dorsal half, starting at the septal pole, and the ventral half, starting at the temporal pole of the hippocampus. The lateral septum has reciprocal connections with the hypothalamus. It also has reciprocal connections with amygdala, bed nucleus of stria terminalis, and periaqueductal grey. The hippocampus proper consists of dentate gyrus, cornu ammonis (CA1, CA2, and CA3), and the hilar region (also called CA4). The dentate gyrus sends mossy fibres to CA3, and CA3 is connected with CA1 via the Schaffer collateral system. These unidirectional connections form the backbone of intrinsic hippocampal circuitry. Hippocampal region CA3 forms and stores representations of events ("event codes"). Acting as a comparator between past and present experience, the hippocampus detects when familiar objects appear in new configurations.
